Wells Fargo & Co. said the amount it may lose due to potential litigation in excess of legal reserves could be as much as $950 million as of Sept. 30, down from $1.2 billion three months earlier and $1 billion a year ago, according to a regulatory filing released by the bank Wednesday.

The estimate is closely watched by investors as a way to gauge whether legal costs are rising or falling versus a bank’s previous expectations. Most banks generally don’t disclose their reserves.